Method for monitoring control and/or regulation of a centrifuge

ABSTRACT

The invention relates to a method for monitoring, control and/or regulation of a centrifuge ( 13 ), for the centrifugal production of a milk product, whereby a device for carrying out the above takes a milk sample of a fluid phase exiting the centrifuge at an outlet from the centrifuge ( 13 ), a material for increasing the light transmission is added to the sample, the light transmittance of the milk sample is recorded, then the fat content determined and then said device monitors, controls and/or regulates the settings of the centrifuge ( 13 ), depending on the fat content determination.

[0001] The invention relates to a method of monitoring, controlling and/or regulating a centrifuge for the centrifugal production of a milk product as well as to a system for implementing the method.

[0002] It is known to, for example, separate milk into skimmed milk and cream by means of centrifuges. Disk separators are generally used for this purpose.

[0003] During the separation into skimmed milk and cream, it is a special goal of the centrifugal separation to minimize the fat content in the skimmed milk as much as possible in order to design the economical yield of the method to be as optimal as possible.

[0004] Unfortunately, the determination of the fat content of cream or skimmed milk is relatively problematic since the skimmed milk or the cream have a white coloring, so that methods for determining the light transmittance of the skimmed milk—as provided according to the invention—cannot be used for determining the fat content but only other high-expenditure (laboratory) processes, such as the process by Röse-Gottlieb and the process by Mojonier with precisions or a reproducibility of 0.03% and 0.015% can be used.

[0005] On the basis of this background, it is an object of the invention to provide a method of monitoring, controlling and/or regulating a centrifuge for the centrifugal production of a milk product as well as a system for implementing the method by means of which the monitoring, controlling and/or regulating of the centrifuge is simplified and a determination of the fat content becomes possible which is as precise as possible, is simpler in comparison to the known laboratory processes and is independent of the latter.

[0006] The invention solves this task with respect to the method by means of the object of claim 1 and with respect to the system by means of the object of claim 7.

[0007] In the case of the method according to the invention, a milk sample is taken at an outlet of the centrifuge from a running-off liquid phase—particularly skimmed milk. Then, a substance which increases the light transmittance is added to the milk sample, the light transmittance of the milk sample is determined, and the fat content is determined therefrom. This information can, in turn, be used for monitoring, controlling and/or regulating the setting of the centrifuge.

[0008] In particular, the light transmittance of the liquid phase, particularly of the skimmed milk, is increased in that a substance which in increases the pH-value—a suitable alkaline solution—is added to the milk sample. Then, the light transmittance can be determined by simply transilluminating the milk sample by means of a light source and a photocell assigned to the milk sample.

[0009] The invention has the special advantage that, by adding the substance which increases the pH-value, it becomes possible in a simple manner to increase the light transmittance of the white sample to such an extent that surprisingly it becomes possible to use an optical method for determining the fat content. Particularly the determination of the fat content can be carried out in intervals by means of a computer in an automated manner. If the computer, in turn, is connected with the control inputs of the actual centrifuge control, or the computer is even used for controlling the centrifuge, it becomes possible to utilize the information not only for monitoring the setting of the centrifuge but also for its controlling and/or also for the regulating as a function of the determination of the fat content. However, a manual monitoring by a person reading a display unit can also be implemented.

[0010] Advantageously, the light transmittance of the liquid phase, particularly of the skimmed milk, is increased in that the substance increasing the pH-value is proportioned and added such that the pH-value of the milk sample is increased to 11-14, preferably 12 -13, and particularly expediently to 13.

[0011] With regard to the system, which can be constructed, for example, as a separate unit and is to be assigned to the centrifuge, a device is correspondingly provided for removing the milk sample from the liquid phase, particularly from the skimmed milk, from the outlet of the centrifuge, as well as a device for adding a substance increasing the light transmittance to the milk sample, and a device for determining the light transmittance content of the milk sample and for determining the fat content. Further, a device for monitoring, controlling and/or regulating the setting of the centrifuge as a function of the determined fat content is preferably assigned to the device for determining the light transmittance.

[0012] Advantageous further developments are contained in the additional subclaims.

[0013] In the following, embodiments will be described in detail by means of the drawings.

[0014]FIG. 1 is a view of a system for implementing the method of monitoring, controlling and/or regulating a centrifuge;

[0015]FIG. 2 is a diagram for illustrating the reproducibility of the measuring results; and

[0016]FIG. 3 is a diagram for illustrating the ratio of the fat content to the display value of the photo cell.

[0017]FIG. 1 illustrates a centrifuge constructed as a disk separator 13 which has an inlet 12 as well as an outlet 14 for cream and an outlet 1 for skimmed milk. After the centrifugal separation of the inflowing milk product into cream and skimmed milk, it is possible to take skimmed milk from the outlet 1 of the centrifuge by way of a sample-taking pipe 2 connected into the outlet 1 of the centrifuge and to guide this skimmed milk into a first storage tank 3. The removal takes place in front of the regulating or constant-pressure valve 23 assigned to or connected here behind the centrifuge in order to take the milk sample from a largely foam-free area.

[0018] A valve 4 is connected in front of the storage tank 3 and, when the storage tank 3 is being filled, is opened until skimmed milk exits by way of a vent pipe 5 which is assigned to the storage tank and leads into the collecting vessel 22. The size of the first storage tank 3 determines the volume which is required or used for the measurement.

[0019] Another valve 9 for letting off the skimmed milk sample from the storage tank 3 is connected behind the storage tank 3. The valve 9 at the outlet of the storage tank 3 is connected by way of a line 16 with a measuring cell 24 which consists of a sample-taking vessel 25, a light source 26 and a photo cell 27, the measuring cell being connected with an analyzing and/or display device 11 (such as a computer, which also controls the measurements).

[0020] In addition, from a second storage tank 18, a liquid for increasing the pH-value of the milk sample discharged from the storage tank 3 is connected in front of the measuring cell 24. From the storage tank 18, the liquid increasing the pH-value or the substance increasing the pH-value can be guided by way of an automatic valve 6 into a third storage tank 7. Again, the size of the third storage tank 7 determines the required volume. The storage tank 7 is filled when liquid exits from an overflow bore 8 which is assigned to the storage tank 7 and leads into the collecting vessel 22.

[0021] As soon as the two storage tanks 7 and 3 have been filled, the valves 9 and 10 connected behind the two storage tanks 7 and 3 are opened. This has the result that the liquids contained in the storage tanks 3 and 7 flow by way of the valves 9 and 10 into the sample-taking vessel 25 and are mixed there. By the addition of the substance from the third storage tank 7, the pH-value of the skimmed milk is increased such that the structure of the protein situated in the skimmed milk is altered such that a light transmittance of the milk sample is achieved.

[0022] Advantageously, the quantitative proportion from the storage tanks 2 and 7 is 2:3, when a suitable alkaline solution is used for increasing the pH-value.

[0023] By means of this light transmittance, the residual fat content can now be determined. For this purpose, the light transmittance is determined, which takes place by irradiating the milk sample by means of the light source 26 and the photo cell 27 arranged relative to the light source behind the measuring cell (not shown here).

[0024] Empirically, a corresponding table can be determined which indicates the dependence of the light transmittance on the residual fat content and can then be stored in a computer, so that, after the measuring of the light transmittance of the milk sample, the cloudiness and thus the fat content are determined by means of a comparison with the stored table. By means of a corresponding adjustment, it is even conceivable to provide the analyzing and/or display device 11 directly with a scale which indicates the residual fat content when a display is implemented there which is proportional to the light transmittance. In this manner, the analysis of the determination of the fat content is further simplified. FIG. 3, which illustrates that the measurements are independent of the temperature and indicates the proportionality between the photo cell display and the residual fat content, demonstrates that this display can be implemented.

[0025] Weak, almost crystal-clear skimmed milk samples have, for example, a residual content of approximately 0.05% fat. In contrast, considerable cloudiness indicates a residual fat content of approximately 0.15%.

[0026] After the measurement, the milk sample is discharged from the measuring cell 24, for example, by way of a valve 20, into the collecting vessel 22.

[0027] By means of the measuring result, the setting of the centrifuge can be changed in the event of deviations from the desired value either manually or automatically - for example, by means of a computer (not shown here) connected to the measuring cell and the disk centrifuge 13.

[0028]FIG. 2 shows that a reproducibility can be achieved within the range of 1/1,000. This precision permits the usage of the new measuring method for controlling and/or regulating separators. In the case of a deterioration of the skimming value, a complete evacuation or a CIP, for example, can be carried out. A reproducibility of less than 0.005% may possibly even be realistic.

List of reference numbers

[0029] outlet

[0030] sample-taking pipe

[0031] storage tank

[0032] valve

[0033] vent pipe

[0034] valve

[0035] storage bank

[0036] overflow pipe

[0037] valve

[0038] valve

[0039] analyzing and/or display device

[0040] inlet

[0041] disk separator

[0042] outlet

[0043] line

[0044] storage tank

[0045] valve

[0046] collecting vessel

[0047] constant pressure valve

[0048] measuring cell

[0049] test taking vessel

[0050] light source

[0051] photo cell 

1. Method of monitoring, controlling and/or regulating a centrifuge for the centrifugal production of a milk product, wherein a) a milk sample is taken at the outlet of the centrifuge from an outflowing liquid phase, b) a substance increasing the light transmittance is added to the milk sample, c) then the light transmittance of the milk sample is determined and the fat content is determined therefrom, and d) as a function of the determination of the fat content, the setting of the centrifuge is monitored, controlled and/or regulated.
 2. Method according to claim 1, characterized in that the light transmittance of the milk sample, particularly of a skimmed milk sample, is increased in that a substance increasing the pH-value is added to the milk sample.
 3. Method according to claim 2, characterized in that the light transmittance of the of the liquid phase, particularly of the skimmed milk, is increased in that the substance increasing the pH-value is proportioned and added such that the pH-value of the milk sample is increased to 11-14.
 4. Method according to claim 3, characterized in that the light transmittance of the liquid phase, particularly of the skimmed milk, is increased in that the substance increasing the pH-value is proportioned and added such that the pH-value of the milk sample is increased to 12-13.
 5. Method according to claim 4, characterized in that the light transmittance of the liquid phase, particularly of the skimmed milk, is increased in that the substance increasing the pH-value is proportioned and added such that the pH-value of the milk sample is increased to
 13. 6. Method according to one of the preceding claims, characterized in that the light transmittance of the milk sample is determined by transilluminating the milk sample by means of a light source and measuring the light intensity by means of a photo cell assigned to the milk sample.
 7. System for implementing the method according to one of the preceding claims, having a) a device (sample-taking pipe 2, storage tank 3) for taking a milk sample from a liquid phase, particularly skimmed milk, from the outlet of the centrifuge (disk separator 13), b) a device (valve 6, 10) for adding a substance increasing the light transmittance to the milk sample, and c) a device (measuring cell 24, sample-taking vessel 25, light source 26, photo cell 27) for determining the light transmittance of the milk sample and for determining the fat content.
 8. System according to claim 7, characterized in that a device for monitoring, controlling and/or regulating the setting of the centrifuge as a function of the determined fat content is assigned to the device for determining the light transmittance.
 9. System according to claim 8, characterized in that a sample-taking pipe (2), which preferably by way of a valve (4) leads into a first storage tank (3), is assigned to the outlet (1) of the disk separator.
 10. System according to claim 8 or 9, characterized in that the sample-taking pipe (2) is connected in front of a constant pressure valve (23) of the centrifuge.
 11. System according to claim 8, 9 or 10, characterized in that the storage tank (3) for the milk sample is connected by way of a valve (9) with an optical measuring cell (24).
 12. System according to one of the preceding claims, characterized in that, in addition, at least one further storage tank (18) for receiving a liquid or a substance for increasing the pH-value of the milk sample is connected in front of the measuring cell (24).
 13. System according to one of the preceding claims, characterized in that the measuring cell (24) has a sample-taking vessel (25), a light source (26) and a photocell (27).
 14. System according to one of the preceding claims, characterized in that an analyzing and/or display device (11) is assigned to the measuring cell (24).
 15. System according to one of the preceding claims, characterized in that the analyzing and/or display device (11) is provided with a scale which directly displays the residual fat content of the milk sample.
 16. System according to one of the preceding claims, characterized by a construction as a separate measuring unit which is to be assigned to the centrifuge. 